I really need help with this Trigonometry Question.

"From an observer O, the angles of elevation to the bottom and the top of a flagpole are 36degrees and 38degrees respectively. Find the height of the flagpole. (Find AB and AC).

-Picture to problem: http://s525.photobucket.com/albums/cc340...

Thanks in advance.

(I have tried twice, but got two different answers... 11 + 12 something...)